The objective of this proposal is to construct novel protein and DNA vaccines that are maximally effective for eliciting potent primary and memory CD8 CTLs and to determine whether such vaccines protect macaques against SIV infection and disease. MHC class I restricted CTLs are thought to play an important role in immunity to retroviruses, and we have discovered that proteins fused to the mycobacterial chaperonin Hsp70 are able to enter into cellular compartments that lead to MHC class I antigen presentation and elicit potent CTLs. Hsp70-SIV fusion proteins and DNA vaccines that express these fusion proteins will be constructed and purified. These constructs will be provided to collaborating investigators to evaluate their ability to elicit potent primary and memory CTLs in mouse models. They will also be provided to collaborating investigators in order to explore the interactions of the heat shock proteins with antigen presenting cells and determine their intracellular fates. Macaques will be vaccinated with those constructs that produce maximal CTL responses in mice. Macaques inoculated with these vaccines will be evaluated for humoral and cellular immune responses in collaboration with Dr. Norman Letvin (Subcontract with Beth Israel Deaconess Medical Center), and for protection against a live challenge with SIV in collaboration with Dr. Michael Wyand (Subcontract with GTC Mason Laboratories).